Party Unity Scores

(31 May 2015)

Party Unity Scores for Democrat and Republican
Members of Congresses 35 - 113 (1857 - 2014)

The files below contain the party unity scores by Congress for every Democrat and Republican
voting on at least 10 party unity votes in the Congress. A party unity vote is defined as one
where at least 50 percent of Democrats vote against at least 50 percent of Republicans. Note
the Presidents can appear in these files because of CQ Presidential Support roll calls for
Presidents Eisenhower through Barack Obama. Earlier Presidents are included because of
Presidential Request roll calls. These roll calls were compiled by an NSF project headed by
Elaine Swift (
Study No. 3371, Database of Congressional
Historical Statistics, 1789-1989). Many of these scores are based upon a small number
of roll calls so use them with caution!).

The format of the files is:

1. Congress Number
2. ICPSR ID Number: 5 digit code assigned by the ICPSR as
corrected by Howard Rosenthal and myself.
3. State Code: 2 digit ICPSR State Code.
4. Congressional District Number (0 if Senate)
5. State Name
6. Party Code: 100 = Dem., 200 = Repub. (See PARTY3.DAT)
7. Name
8. Party Unity Score
9. Number of Party Support Votes Member Voted with Party
10. Total Number of Party Support Votes Member Voted on

Party Unity Scores by Chamber for All Two-Party Systems

Below is a file containing the Party unity scores for the House and Senate. A Party Unity
vote is one that pits a majority of one Party against a majority of the opposite
Party.

The format of the file is:

1. Congress Number
2. First Year of the Congress
3. Number of Roll Call Votes in the House
4. Number of Party Unity Roll Calls (at least 50% of one Party vs. 50% of the opposite Party)
5. Percentage of Party Unity Votes
6. Proportion of Federalists/Whigs/Republicans voting with the majority of their Party
7. Proportion of Jeffersonian-Republicans/Democrats voting with the majority of their Party
8. Number of Roll Call Votes in the Senate
9. Number of Party Unity Roll Calls
10. Percentage of Party Unity Votes
11. Proportion of Federalists/Whigs/Republicans voting with the majority of their Party
12. Proportion of Jeffersonian-Republicans/Democrats voting with the majority of their Party